Allergen avoidance is a risk-free therapy for asthma that has been shown repeatedly in clinical trial to reduce asthma symptoms and bronchial hyperresponsiveness. We propose to conduct the first trial of the effectiveness of this important adjunct therapy, comparing a home-based allergen control education program to customary education program. We will recruit 240 children aged 6-17 years who have asthma that is currently active. Each child and their family will undergo a baseline evaluation that will include questionnaires, allergy skin tests, spirometry and a home visit to evaluate allergen control behaviors and to collect dust from the child's bedroom to measure concentrations of house dust mite, cat, dog and cockroach allergens. After receiving traditional allergen control education in the clinic, participants will be randomized to receive either usual care in a pediatrician's office or a home-based behavioral educational and support program provided by trained Evironmental Control counselors. Support will include identification of environmental risk factors for the family, modeling and teaching control behaviors, problem solving with the family, and encouraging self-efficacy. Both office-based control and home-based intervention groups will be offered discounted environmental control supplies and cockroach extermination. Children and families will be assessed in clinic visits by a separate evaluation team at 6 to 12 months post randomization. Home visits will be repeated by the evaluation team at 6 to 12 months. Primary outcome will be changes in changes in Asthma-related Quality of Life measures and target environmental allergen levels in the home. Secondary outcomes include adherence with environmental control recommendations, changes in Rhinoconjunctivitis-related Quality of Life measures, FEV1, changes in environmental allergens other than the targeted allergen, self efficacy for environmental allergy control and healthcare utilization.